There is a known optical tridimensional modeling method to form a tridimensional object having a structure of an integrally laminated cured resin layer, being formed by repeating the step of forming the cured resin layer through the selective irradiation of light to a radiation-curing liquid substance (a liquid resin composition) (refer to Patent Documents 1 to 4). A typical example of this optical tridimensional modeling method is explained as follows.
First, a cured resin layer having a specified pattern is formed by selectively irradiating light such as ultraviolet laser to the liquid surface of a radiation-curing liquid resin composition held in a container. Then, by supplying a radiation-curing liquid resin composition in a quantity of a single layer thereof onto the cured resin layer and selectively irradiating light onto the liquid surface, a new cured resin layer is formed integrally onto the previously formed cured resin layer in a continuous fashion with each other. And, by repeating the above steps for the prescribed number of cycles with or without changing the light-irradiation pattern, an integrally laminated tridimensional object by a plurality of cured resin layers is formed.
According to this optical tridimensional modeling method, the target tridimensional object can be provided easily in a short time no matter how complicated its shape is. Such technology is extremely useful at the experimental stage in developing new products in the automobile industry and the consumer-electronics industry, and is becoming an essential means for shortening the development period and for reducing costs.
Conventionally, as radiation-curing liquid resin compositions used in the optical tridimensional modeling method, the resin compositions represented by [1] to [3] as described below have been introduced:    [1] a resin composition containing radical polymerizable organic compounds such as urethane(meth)acrylate, oligoester(meth)acrylate, epoxy(meth)acrylate, thiol, en compound, and photosensitive polyimide (refer to Patent Documents 5 to 7);    [2] a resin composition containing cationic polymerizable organic compounds such as epoxy compound, cyclic ether compound, cyclic lactone compound, cyclic acetal compound, cyclic thioether compound, spiro-ortho-ester compound, and vinylether compound (refer to Patent Documents 8); and    [3] a resin composition containing radical polymerizable organic compounds and cationic polymerizable organic compounds (refer to Patent Documents 9 to 14).
In Patent Documents 15 and 16, there are described antioxidants as components, which can be added to a radiation-curing liquid resin composition used for optical tridimensional modeling.
In the compositions of the above-mentioned [2] and [3], a cationic polymerization initiator of triaryl sulfonium salt type is generally used.

Commercially available products of this compound comprise UVI-6974, UVI-6976 (manufactured by D.A. W. CHEMICAL CO., INC.), CPI-6976 (manufactured by Aceto Corporation), and the like.    Patent Document 1: JP-A-60-247515    Patent Document 2: JP-A-62-35966    Patent Document 3: JP-A-62-101408    Patent Document 4: JP-A-5-24119    Patent Document 5: JP-A-1-204915    Patent Document 6: JP-A-2-208305    Patent Document 7: JP-A-3-160013    Patent Document 8: JP-A-1-213304    Patent Document 9: JP-A-2-28261    Patent Document 10: JP-A-2-75618    Patent Document 11: JP-A-6-228413    Patent Document 12: JP-A-11-310626    Patent Document 13 : JP-A-11-228610    Patent Document 14: JP-A-11-240939    Patent Document 15: JP-A-8-256062    Patent Document 16: JP-A-2003-240939